I was one of such speculators who got disappointed at the end. There are teams that gets so mastered to a particular team such that whenever they meet, just expect some sort of fun because both team does put out their best anytime they are meeting and so it usually will look like they will do so well and that was the case with Barcelona and Inter Milan that inspired my speculations for them to get to the finals with those performances of theirs seeing that they also had a good squad depth as at the time.
Football can be really unpredictable as we already know and the fact that Inter's exceptional performance against Barcelona didn't translate to the final just like most people expected made the outcome even more thrilling to some and to others disappointing.
While it was disappointing in one side, it's great that you've also learner from your experience and can reflect on what actually went wrong. At least next time, it'll enable you make more reasonable and informed choices when making your predictions. Football is full of surprises, which is why we shouldn't be overconfident with whatever predictions we're making, regardless of how certain it may be, at least this would help one make more realistic choices.
It is full of surprises, given that Inter initially played well but then performed poorly in the final and were unable to compete with their opponents. I still do not understand how they conceded five goals. I understood that when they conceded too many goals in two consecutive matches against Barcelona, but they also scored a lot, it's surprising that they couldn't do anything against PSG.